It sounds like you're already seeking a lot of the right help. I'm not surprised your orthodontist isn't concerned about how you breathe or speak; they're usually just concerned with preserving their work. Most of them won't even try to correct a root problem, they just focus on addressing symptoms. If the whole orofacial symptom is working correctly, there should be no need for a retainer. The tongue is supposed to be nature's retainer. It's very good that you can breathe through your nose. It doesn't sound like allergies or asthma is a chronic issue in your case, so I agree, it doesn't appear to be a continuing factor, but your mouth breathing is. That needs to be corrected. If you're chewing incorrectly and chewing gum for several hours a day, that could be contributing to jaw tension. But it also may be a catch-22 because chewing gum can strengthen your facial muscles, but chewing incorrectly can damage them too. Have you seen an ENT? If so, has s/he ever prescribed muscle relaxers for you? Have you seen an SLP that has also been trained in myofunctional therapy? I understand you have social anxiety, and putting it aside is easier said than done. However, I recommend that you even though you have it with the general public, please try to forget about it when seeking medical help. Not all medical professionals do their job well, but they will try to help you. When interacting with them, don't try to hide your problems or perform for them. If you're not getting results from a provider, stop seeing the provider, but don't stop seeking help. Try someone new. Continue to educate yourself on conditions that resemble your own. There's a lot of information online, but don't immediately believe it. If you find information that excites you, corroborate it through journals published in an authoritative archive. My go-to source is https://www.ncbi.nlm.nih.gov/pubmed.